wifi: ath12k: don't activate more links than firmware supports

In case of ML connection, currently all useful links are activated at
ASSOC stage:

        ieee80211_set_active_links(vif, ieee80211_vif_usable_links(vif))

this results in firmware crash when the number of links activated on the
same device is more than supported.

Since firmware supports activating at most 2 links for a ML connection,
to avoid firmware crash, host needs to select 2 links out of the useful
links. As the assoc link has already been chosen, the question becomes
how to determine partner links. A straightforward principle applied
here is that the resulted combination should achieve the best throughput.
For that purpose, ideally various factors like bandwidth, RSSI etc should
be considered. But that would be too complicate. To make it easy, the
choice is to only take hardware modes into consideration.

The SBS (single band simultaneously) mode frequency range covers 5 GHz
and 6 GHz bands. In this mode, the two individual MACs are both active,
with one working on 5g-high band and the other on 5g-low band (from
hardware perspective 5 GHz and 6 GHz bands are referred to as a 'large'
single 5 GHz band). The DBS (dual band simultaneously) mode covers 2 GHz
band and the 'large' 5 GHz band, with one MAC working on 2 GHz band and
the other working on 5 GHz band or 6 GHz band. Since 5,6 GHz bands could
provide higher bandwidth than 2 GHz band, the preference is given to SBS
mode. Other hardware modes results in only one working MAC at any given
time, so it is chosen only when both SBS are DBS are not possible.

For each hardware mode, if there are more than one partner candidate,
just choose the first one.

For now only single device MLO case is handled as it is easy. Other cases
could be addressed in the future.

Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.1.c5-00284-QCAHMTSWPL_V1.0_V2.0_SILICONZ-1
Tested-on: QCN9274 hw2.0 PCI WLAN.WBE.1.4.1-00199-QCAHKSWPL_SILICONZ-1

Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com>
Reviewed-by: Vasanthakumar Thiagarajan <vasanthakumar.thiagarajan@oss.qualcomm.com>
Link: https://patch.msgid.link/20250522-ath12k-sbs-dbs-v1-6-54a29e7a3a88@quicinc.com
Signed-off-by: Jeff Johnson <jeff.johnson@oss.qualcomm.com>

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